The fabrication of a semiconductor device involves a plurality of discrete and complex processes. The semiconductor substrate typically undergoes many processes during the fabrication process. As a substrate is being processed, the substrate is typically clamped to a chuck. This clamping may be mechanical or electrostatic in nature. The electrostatic chuck traditionally consists of a plurality of layers. The top layer, also referred to as the top dielectric layer, contacts the substrate, and is made of an electrically insulating or semiconducting material, since it produces the electrostatic field without creating a short circuit. Methods of creating this electrostatic field are known to those skilled in the art. The electrostatic force can be generated by an alternating voltage (AC) or by a constant voltage (DC) supply. To create the electrostatic force, a plurality of electrodes may be disposed beneath the top dielectric layer. The plurality of electrodes is constructed from an electrically conductive material, such as a metal.
In certain applications, ion implantation may result in crystal defects and amorphization. This crystalline damage can often be restored by thermal processing, known as annealing. However, for certain high dose implants and device structures, typical post-implant annealing may not be sufficient to restore all the damage caused by the implantation. Heating the substrate during the implant process is known to reduce damage to the substrate and to preserve more of the crystalline structure to facilitate regrowth during the anneal process.
Substrates are typically heated by contact, such as through the use of a gas trapped between the workpiece and the chuck, such as when the substrate is held in place through electrostatic forces. The substrate may also be directly heated by the chuck. In both embodiments, heat is applied to the lower surface of the substrate by the chuck. These methods may suffer from certain drawbacks. For example, the temperature to which the electrostatic chuck is heated may be excessive and place thermal stresses on the electrostatic chuck itself. This may reduce the reliability of the electrostatic chuck, and may also add significant cost to the electrostatic chuck.
It would be beneficial if there were an electrostatic chuck that could be used to clamp and heat the substrate, without suffering from these disadvantages. Further, it would be advantageous if that electrostatic chuck could also cool the substrate after the processing is completed.